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Police forces across the United Kingdom effectively campaigned to use a face scanning system known to be biased against females, youths, and individuals from minority ethnic backgrounds, following complaints that a less biased version generated fewer investigative leads.

How the System Works

UK forces utilize the national police database to conduct searches using historical face recognition. This process entails comparing a “probe image” of a suspect against a repository of over 19 million mugshots to identify possible hits.

Admitted Bias

The Home Office admitted last week that the technology was biased. This acknowledgment followed a review by the government's National Physical Laboratory determined it misidentified Black and Asian people and females at much greater frequency than white men. The Home Office said it “took steps on the findings”.

“It prompts the issue of whether facial recognition only becomes useful if users accept biases in race and gender. Convenience is a weak argument for overriding fundamental rights.”

Known Issue

Official papers reveal that this discriminatory flaw has been known about for over twelve months. Furthermore, law enforcement lobbied to reverse an initial decision that was intended to address the problem.

Police bosses were informed of the system's bias in September 2024. The government-ordered NPL review found the system was more likely to produce false positives for photos of females, Black people, and those under 40 years old.

A Reversed Decision

In response, the national police leadership body mandated that the accuracy setting required for potential matches be raised to a level where the bias was greatly diminished.

However, this decision was reversed the following month after forces complained that the modified technology was generating fewer “useful lines of inquiry”. NPCC documents show the stricter setting reduced the proportion of queries that yielded potential matches from over half to a mere under 15%.

Severe Disparities

Although the authorities declined to specify what threshold is currently used, the recent independent review discovered the system could generate incorrect matches for Black women nearly a hundred times more frequently than for white women at certain settings.

The Home Office commented on these findings: “Our evaluation found that in a limited set of circumstances the software is more likely to incorrectly include some demographic groups in its match reports.”

Balancing Utility and Fairness

Describing the impact of the brief increase to the system's confidence threshold, the police records state: “The change significantly reduces the impact of discrimination across protected characteristics of race, generation and sex but had a significant negative impact on police efficiency”. The documents add that forces argued that “a previously useful tool now delivered results of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has opened a ten-week public review on its plans to expand the use of biometric scanning systems. Policing minister the relevant minister has labeled the tool as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the independent scrutiny and oversight board for the national policing equality strategy, commented: “There was very little consideration in equality strategy sessions of the facial recognition rollout despite obvious cross-over with the strategy's goals.

“This disclosure demonstrate once again that the anti-racism commitments the police has undertaken through the equality initiative are failing to be integrated into broader operations. Our reports have warned that innovative tools are being rolled out in a context where racial disparities, inadequate oversight and faulty information gathering already persist.

“Any use of facial recognition must meet strict national standards, be independently scrutinised, and prove it reduces rather than compounds ethnic bias.”

Home Office Response

A government representative said: “The Home Office takes the findings of the study with utmost gravity and we have implemented changes. A new algorithm has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be tested in the coming months and will be subject to further assessment.

“The foremost aim is ensuring public safety. This gamechanging technology will support officers to put criminals and rapists behind bars. There is officer review in every step of the procedure and no arrest or charge would be pursued without specialist personnel carefully reviewing the output.”